Japanese Patent Application Laid-Open No. 2010-162804 discloses an image forming apparatus in which an image is formed by ejecting ink from nozzles while an ink jet head reciprocates in a scanning direction. The image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2010-162804 comprises nozzles for black arranged at half the interval of nozzles for color, in which the nozzles for black and the nozzles for color eject ink while the ink jet head reciprocates in the scanning direction and a recording sheet is conveyed by the distance corresponding to the interval of five nozzles for black every time a moving direction of a carriage is inverted, to form an image on the recording sheet.